Move Precision, Recall and F1-score computation from `AgcManagerDirect` to a separate function that can be tested. Bug: webrtc:12774 Change-Id: Iba20f153a72b7f957bf938e0642055d421045c02 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231228 Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Reviewed-by: Hanna Silen <silen@webrtc.org> Cr-Commit-Position: refs/heads/main@{#34933}